The millionaire Republican presidential candidate Steve Forbes, whose family is a large benefactor of Princeton university, yesterday cut off funding to the celebrated Ivy League university over its appointment of the controversial philosopher Peter Singer as its first professor of bioethics.

His move comes the day after a rally of mainly disabled protesters chained themselves to Princeton's administration building as the Australian-born Mr Singer began to teach his first classes of the term.

His arrival has sparked a series of campus protests because of his high-profile notoriety as an advocate of euthanasia for some disabled infants.

But Mr Forbes' decision is certain to politicise the dispute even more sharply. The conservative publishing millionaire had earlier resisted pressure to withdraw his support from Princeton over the issue, but yesterday he reversed that decision while campaigning in California.

"Though I fondly remember my days as a student at Princeton, and though I am a trustee of this university, I have given no money to Princeton since Peter Singer was appointed to be a professor of bioethics, and I pledge to you today that so long as Peter Singer remains a tenured professor there, I will not financially contribute to Princeton university," Mr Forbes said in a statement.